Drupal6 import support

Django management command for importing blogs from Drupal 6 installation (to be more precise, from Drupal 6 database) into Zinnia.

One catch is that I'm relying on using SQLAlchemy for doing ORM with Drupal's database.

As a test base I've used my own Drupal installation, which has only one user, but I've tried to design the command to support multiple authors etc.

One small catch is that command won't work well for iterations, mainly because of the way I've done mapping of categories. The categories are imported in such a way that you can have same-named categories in different category trees, while the code will make sure assignment of categories to entries will be the same as in case of Drupal.